U.S. Pat. No. 4,946,494 discloses a pyridinesulfonylurea derivative useful as an effective ingredient of a herbicidal composition, which is, however, different in the substituent at the 6-position of the pyridine ring in terms of chemical structure from the compound of the present invention.
EP 451,468 corresponding to U.S. Pat. No. 5,139,565 and PCT WO91/10660 disclose a pyridinesulfonylurea derivative as an active ingredient of herbicidal compositions. This compound is different from the compound of the present invention in the position of an N-substituted sulfamoyl group.